Retaining documents with larger size but low DPI - how do we meet our standards?

asked on January 31, 2024

Hello all,

I live and work in Oregon, where we are obligated to store official records with a minimum 300 DPI (I believe this is pretty standard). We have recently been making a push to make sure that our documents meet that requirement, and identify those that do not. Most do.

I have been finding that imported images, however, can be tricky. Images are often included in a record as an attachment or support to some official document, and I'm honestly uncertain how that fits with our record requirements. That aside, I find that these image files are often larger in size, but low in DPI. One recent example has a size of 3024x4032, but a mere 72 DPI.

Is there a point at which image size compensates for image DPI? I haven't thus far found any guidelines that address that. Does anyone else have experience with this issue, or suggestions on what we might do to ensure that we are meeting our electronic document obligations?

1 0

SELECTED ANSWER

replied on February 1, 2024

DPI is, in my experience, only meaningful for images that come from a physical scanner, and that is likely the scenario that your standards are meant to target. The challenge is that more and more, images are not captured by a literal scanner, or they pass through software layers that don't fully preserve metadata like dpi. If you capture a document like a bank check using your camera, you will fill the frame with the check so that the captured image will be approximately the same number of pixels no matter the physical size of the check - there's no way to know the dpi without independently knowing the size of the paper.

An image that's 3024x4032 at 72 dpi implies that the source document was 42x56 inches. That's not impossible, but it seems more likely that some piece of software along the way lost track of the actual dpi and inserted a default value. If the source document was letter size, 3024 pixels wide is a very high quality scan. It would be interesting if you could figure out the full provenance of that 3024x4032 72 dpi image: what the source document was, how it was captured and processed, etc.

3 0

replied on February 1, 2024

Thanks for the response Brian! I'm still unsure how these types of entries correspond to our resolution requirements, or effectively filter out documents that are "good enough" due to size, but what you're saying here makes good sense and eases my concerns a bit.

Regarding the history of the example entry, it was a photograph that was uploaded as an attachment to a Forms process, then saved to the repository via Forms.

0 0

replied on February 1, 2024 • Show version history

I agree with Brian, the DPI is not a value that should be considered independently or in every context because it is only a part of the story.

Typically, rules like this are meant for scanning because they're saying you should have "300 pixels for each inch of the scanned document" but that doesn't really apply to something that was already digital to start with.

An 8.5x11in page would be 2550x3300 pixels at 300 DPI; the "quality" of the image comes from the number of pixels and the format/compression.

However, after the image is captured/created, DPI is really just a reference for the scaling of the image as Brian described.

For example, say you have two images of the same document, one is 1275x1650px at 600 DPI, and the other is 2550x3300px at 300 DPI.

Practically speaking, the 600 DPI version would much worse quality than the 300 DPI version because it has way fewer pixels.

Long story short, DPI only truly matters during scanning/capture. Once you have the pixel data, DPI is little more than a scaling reference.

1 0

Question

Question

Retaining documents with larger size but low DPI - how do we meet our standards?

Answer

Replies

Sign in to reply to this post.